Mole and fluid-driven motor therefor



oct. zo, 1959 A. GAL mL 2,909,155

MOLE AND FLUID-DRIVEN MOTOR THEREF'OR Oct. 20, 1959 A, GAL EI'AL 2,909,155

MOLE AND FLUID-DRIVEN MOTOR THEREFOR I Filed March 28. 1957 3 Sheets-Sheet 2 l @d i I INVENTORS f7 .3 f7 ./5 BY J0 l 'g @5,4L06l? ATTORNEYS Oct. 20, 1959 A. GAL ETAL.

Mou: AND FLUID-DRIVEN Mo'roR THEREFOR 5 Sheets-Sheet 3 INVENTOILS` 64j.; 6L, /'7 `Q. 20 ATTORNEYS Filed March 28, 1957 United States Patent O MOLE AND FLUID-DRIVEN MOTOR THEREFOR Andrew Gal and Karol Gerber, Forest Hills, N.Y., as-

signors to Rockdrill Industries, Inc., New York, N.Y., a 'corporation of New York Application March 28, 1957, Serial No. 649,169

'13 Claims. (Cl. 121-25) .This invention relates to a mole, and is particularly concerned with a drilling mole, that is to say, a mole which is attached to the end of a rotating string and is designed to perform deep drilling 'operations beneath the surface of the earth. The invention further is concerned with a novel fluid-driven motor for actuating the mole and which also is useful in other mechanisms, e.g. air hammers, Where a rapid succession of blows is needed.

Specifically, the present invention discloses a deep drilling earth mole of the type which utilizes fluid pressure to create a rapid succession of powerful impacts that are applied to an earth-boring tool while the latter is rotating.

It has been proposed heretofore to employ in such a machine a hydraulic percussion motor utilizing, instead of springs and mechanically operated valves to create the desired reciprocating movement, a slider translatable within a piston that operates inside a cylinder. An example of such a mole is illustrated in issued United States Letters Patent, 2,773,483, for Drive Mechanisms for Percussion Tools Operated by a Pressure Medium, the same being dated December ll, 1956.

Although machines of the type illustrated in said patent have proved quite useful in earth drilling operations, such, for instance, as the drilling of oil wells, they have several drawbacks. For example, the machines disclosed in said patent, as is common in apparatuses wherein a piston is reciprocated by fluid pressure, employ a piston rod that extends from one end of the piston and thereby blocks off a considerable area of the piston from exposure to the high pressure fluid. Consequently, the work effort of the piston is uneven, that is to say a machine of this character creates an asymmetrical series of blows which shorten the life of the machine and the tools driven by it. In addition, the displacement on both sides of the piston is non-uniform, this being particularly undesirable where a non-compressible fluid is used. Furthermore, in such machines a particularly difficult problem is presented in sealing the piston rod against leakage, and it has been found that there is a very substantial loss of pressure through the piston rod glands which substantially lowers the efficiency of the machine, lessens the velocity of the impact' blows, and ultimately'often results in a blowout of a high pressure seal.

Another disadvantage of previous machines, as, for example, those illustrated in the aforesaid patent, is the slow operation and heavy Weight of the control slider. Due to the fact that such a slider has a substantial length necessitated by its complex functioning and ducting and further due to its use for guiding high pressure fluid in a large number of paths, the length of the sliderv is abnormally great and its Weight, correspondingly, substantial. Accordingly, even though the fluid employed is at high pressure, the slider accelerates slowly, its acceleration being further impeded Iby the substantial friction generated over the long length of the slider. Hence, since the slider mustrexperience a full stroke before the piston 2,909,155 Patented oct. zo, 1959 ice here referring to is far less than desired, so that the machine suffers a corresponding loss in efficiency.

In connection with the slider itself, it has been found heretofore that the construction thereof is quite complex inasmuch as its functions are so varied, and therefore the sliders have been expensive to make, expensive to maintain and, despite this, have a comparatively short life.

A further disadvantage of the previous moles employing high pressure fluids and characterized by the absence of springs and mechanically operated valves is their general overall complexity. Thus, referring to the mechanism of the aforesaid patent, it will be observed that to conduct properly the high pressure fluid to the sundry places it had to enter for proper operation of the mole, it was necessary to provide a large number of long internal conduits separate and apart from the slider, Vthe piston, and the barrel in which the piston operated. It also was necessary to provide glands or other types of pressure seals in a great number of places. i Inasmuch as the mole had to operate within small diameter bores, conventional seals and glands could not be employed and itwas necessary, instead, tov reduce the sizes of allthe parts and to employ extremely close tolerances so that tiny clearances could be obtained whereby to create the sealing effect desired; However, since the lengths of the moving parts were, as noticed above,'substantial, since the tool was working out of sight and outiof bearing where danger signals were not apparent, since high pressure was detrimental to the lapped surfaces at the journals and bearings, and since the mole, dangling as it was from the end of a long string deep in the earth, was subjected to torsional and bending forces, the many glands and seals stayed tight for only a short time, clearances between the sliding parts quickly deteriorated, and the efficiency of the mole rapidly fell off as did the rapidity and force of the impacts.

Still another disadvantage of previous moles of the character described was that when the mole Was lowered into the earth after having been removed from the bore for any reason, or if there was a momentary failure Yof fluid pressure, or if the hydraulic pressure was deliberately cut off at some time as, for instance, at the end of working hours, the great pressure of the fluid at theboty tom of the still incompleted bore tended to force the mud in the bore backward through the mole, thereby introducing into the mole abrasive particles which caused serious damage to the finely machined parts.

`It is an object of our invention to provide a highly improved mole of the character described, that is to say a hydraulically operated mole characterized by the absence of springs and mechanically operated valves wherein all of the foregoing disadvantages are eliminated.

Itis a further object of our invention to provide a highly improved fluid-driven motor which can be usedv in such a mole or to drive other percussion impact machines. One of the phases of our invention deals with the uneven stroking o'f the piston which, as noted above, has` been caused by unequal end surface'work areas. It is an object of our invention to eliminate such uneven stroking by incorporating a singular construction for the piston and an unusual connection between the piston, the stationary parts of the motor and the percussive output element, fwhereby the presence of a solid piston rod secured to the piston is eliminated. We thus, are able to do away with not only the uneven stroking just mentioned,

but also the necessity of providing thetspecial pressure seals and glands for the piston rod, the deterioriation of'V which lower the efficiency of the motor. It is an ancillary object of this phase ofour invention to provide iny a' mole of the character described a cylinder-like power end Y for -a piston and to operatively associate this end with what is in reverse a stationary piston so that the desi-red elimination of the solid piston rod is secured.

Another phase of our invention relates to the slider valve. It is ari-object thereof to provide in a motor of the character described a slider valve of extremely simple construction, light weight and short length, so that the valve is rugged, rapidly acceleratable and quick moving, and further, so that it is able to function with a shorter stroke. It is another object of our invention to provide a slider valve for a motor of the character described wherein the reversal of the motion of the valve is very simply accomplished and the number of associated ducts are appreciably4 lessened, and further, in which certain of the ducts perform dual functions, that is to say, both control motion of the slider land concurrently feed high pressure fluid to the opposite ends of the piston. It is another object of this phase of our invention to provide for a motor of the character described an arrangement such that the high pressure fluid always is supplied to a central portion of the slider valve whereby it merely is necessary to divert the fluid in one direction or `another and the fluid continuously streams into this portion of the valve and on through the piston work chambers to the outlet of the mole and into the bore, thus creating a continuously ejected stream of fluid and eliminating stoppage of the fluid and the necessity of expending energy repeatedly to start flow of the uid upwardly in the bore. It is a further object of this phase of our invention to provide a slider of the character described which, by a construction having the foregoing characteristics, substantially increases the rate and force of the impacts.

It is another object of our invention to substantially reduce the numberY of sealing points by changing the slider and piston as above described, and thereby not only to reduce the cost and lower the upkeep for the motor, but also to substantially lessen power sapping leakage. More particularly, it is a subsidiary object of our invention to provide a motor of the character described in which packing is utilized in an unusual way to reduce the diameter and complexity of the tool without affecting the excellent sealing action secured and having the further advantage that lit enables the length of the piston to be reduced.

Another phase of our invention deals with the conduction of the shock blows to the tools, it being an object thereof so to construct the mole that the transmission of the percussive blows is unirnpeded by restraining forces generated by the torsion to which the mole is subjected. Thus, heretofore the piston has been formed as a tool holder. Since the tool was required to turn, it was necessary to couple the piston and the turning string in such a fashion that the piston was turned by the string to rotate the tool in turn. As a result, substantial friction was developed along axial slideways for the piston, and the consequent restraint against axial movement of said piston substantially slowed down the velocity of the piston and lessened its rate and force of lmpact.

In accordance with an object of this latter phase of our invention, the mole is provided with a break between the piston and tool holder, that is to say, these two parts are separate from and independent of one another whereby the torsion required for movement of the tool holder is not transmitted through the piston and, accordingly, the piston is not subjected to the frictional restraint hereinabove mentioned. It is an additional object of this phase of our invention to provide a mole of the character described which, by separating the piston and the tool holder las in the manner just mentioned, enables a particularly useful drilling function to be performed as, for instance, eliminating upward blows when drilling for cores.

Other objects of our invention in part will be obvious and in part will be pointed out hereinafter.

Our invention accordingly consists in the features of construction, combinations of elements and arrangements of parts, which will be exemplified in the mole and motor hereinafter described and of which the scope of application will be indicated in the appended claims.

ln the accompanying drawings, in .which is shown one of the various possible embodiments of our invention,

Fig. l is a longitudinal central sectional view through the new hydraulic motor of a mole constructed in accordance With our invention and showing the piston at the beginning of its upward stroke, said gure being taken along the lines 1 1 of Figs. 4-10;

Fig. 2 is a view similar to Fig. 1, but showing the piston at the beginning of its downward stroke;

Fig. 3 is a longitudinal central sectional View through the tool holder of said mole, said figure being taken along the lines 3 3 of Figs. ll-l3;

Figs. 4, 5, 6, 7, 8, 9 and l0 are transverse sectional views taken substantially along the lines 4 4, 5 5, 6 6, 7 7, 8 8, 9 9 and itl-1t), respectively, of Fig. l, and showing various Vdetails of the hydraulic motor;

Figs. 1l, 12 and 13 are transverse sectional views taken substantially along the lines 11-11, 12 12, and 13 13, respectively, of Fig. 3, and showing various details of the tool holder;

Fig. 14 is a side View, to an enlarged scale, of one form of bit which may be mounted on the tool holder;

Fig. l5 is a View similar to Fig. 14, but showing another form of bit;

Fig. 16 is a view similar to Fig. 14, but showing still Ianother form of bit;

Fig. 17 is a longitudinal central cross-sectional half view, drawn to a larger scale than that of Fig. 1 for the purpose of clarity, of the hydraulic motor, and showing the slider valve and piston in their lowermost positions, as in Fig. 1;

Fig. 18 is a view similar to Fig. 17, but showing the piston in the middle of its upward stroke and the slider valve still in its lowermost position relative to the piston;

Fig. 19 is a View similar to Fig. 17, but showing the piston approaching its uppermost position and the slider valve ready to begin its upward travel relative to the piston; and

Fig. 20 is a View similar to Fig. 17, but showing the piston at the beginning of its downward stroke and the slider valve in its uppermost position relative to the piston.

Referring now Iin detail to the drawings, the reference numeral 30 denotes a mole embodying our invention. Said mole includes a casing 32 of tubular yshape in threaded engagement at its upper end with a central apertured plug 34. At its top end the plug is threaded for engagement with a pipe that extends upwardly through a bore in the earth, the pipe being secured to a Iig on the earths surface which turns the pipe and mole about their longitudinal axes. Liquid under pressure as, for example water in which a clay type mud is suspended, is introduced through the plug 34 to the upper interior portion of the casing 32 by means ol a conduit 36. Y

The lower end of the casing is internally tapped to threadedly engage the external wall of a cylinder 38 that turns with `the casing, the internal working length of the cylinder extending from plane a to plane b as indicated in Fig. 1. Said cylinder optionally includes a flange 40 against which the lower .end of the casing bears. It will be noted that the external surface of the upper end of the cylinder is of somewhat reduced diameter to form an .annular space 42 for passage of high pressure fluid.

A piston 44'is slidable within the cylinder. Conveniently, said piston is fabricated in two parts, to wit,

an upper part 46 and a lower` part 48. `Said piston not only slides within the cylinder but has a portion extend-- ing well below the cylinder, said portion constituting a cylindrical skirt 50, the 'internal diameter of which is the same as the external diameter ofthe parts vof the piston operating within the cylinder.

The space between the top of the piston vand a cap 52 which closes the upper end of the cylinder, constitutes an upper working chamber 54. g

Tol seal the upper end of the piston and thereby at a given portion' of the cycle maintain iluid under pressure in the working chamber 54, we provide an upper work its way through the tight joint'between the sleeve and the tube 58. A lock nut 64 likewise threaded on the tube 58 maintains the rings in their tightenedposition. The sleeve 56, 'due to the axial compression exerted thereon, will tend to have a slightly bulged external surface, and it is this. surface which rides on the iinside of the cylinder 38"and forms the seal for the upper working chamber 54.

' The upper end of the tube 58 is snugly slidably engageable with a stub pin 66 extending downwardly fromv the cap 52 into the work chamber' 54, said pinl being provided to cushion the 'stop of the piston at the upper end of its stroke in a manner which will be described hereinafter.

Slidable' within the skirt S0 is another rubber sleeve 68= which, like the sleeve 56, is Vcaughtand squeezed between a pair of 'rings 70', 72, these latter being screwed on -a rod 74. The clamps a're held in tightened position by a lock nut 76' threaded on said rod. The rubber sleeve engages the inner wall of the skirt 50 as the same slides up and down during to and from movement of the piston, and said sleeve forms in cooperation with the skirt in the region over the upper end of the rod a'lower work chamber 78.

Obviously the mole is operated by alternatively supplyig fluid under pressure vto the two work chambers 54, .78. It will be observed that both of these work chambers are of the same diameter and provide the same working face for the pressure fluid so that the upward and downward strokes of the piston are 'alike in force. This has been accomplished by elimination of the solid piston rod which customarily is connected'to the lower working face of the piston, this being the face that is mechanically secured to the tool holder.-

In accordance with our invention, this connection has been eliminated by the use of the skirt. However, it still is necessary to effect a working connection, Le., a kinematic train, from said skirt to portions of the mechanism at the lower end of the mole by means of which impacts, i.e., shocks, can be transmitted to the bit carried by the mole. l

To the foregoing end we provide a unique mechanical power take-olf for the skirt. More speciiically, the lower end of the skirt is internally threaded to receive -a bushing 80. In turn the bushing is tapped to engage the threaded upper end 82 of a rod-like hammer 84. Said end of the hammer is formed with a plurality of longitudinally extending radial slots 86. Slidable in the p slots are a series of Iribs 88, the upper ends of which are integral with the rod 74 and the lower ends of which are integral with a flange 90. Thus the hammer is free to slide axially relative to the rod 74 while the rod is maintained 4in stationary position by fixing the flange 90 relativetlo` the casing 32. This latter is performed by catching .the ilange beneath a shoulder 92 on a sleeve 94 that is screwed to the lower externally threaded end of the cylinder 38. The sleeve 94 extends beneath the ttiange and is'tapped to engage the male threaded upper end of a second sleeve 96 wherebyto secure the flange 90 between the two sleeves. l

It now will be apparent that reciprocation of the piston is transmitted -to the hammer 84 to cause reciprocation thereof, but that this transmission of power is achieved without the use of a conventional piston rod secured and partially obstructing the lower working face` of the piston. f 'Y l Y It may be mentioned moreover at this pointof the de-v scription that, although' the stationary longitudinal ribs 88 co-act with the slots 86 in the hammer 84 to prevent rotation of the latter relative to the casing l32, no torsional load is transmitted throughsuch sliding connection inasmuch, as later will be seen,'the hammer 84 is notf firmly mechanically connected to' the toolk holder andA such torsional load portion is transmitted by 'the sleeveV connecting the bore 98 with an' annular space 104 around the skirt, i.e., between the skirtpand the sleeve 94.

The differential slider valve is specially -shaped in ac-A cordance with our invention, and more particularly. includes a head 106 at its upper end and an enlarged midsection 108 intermediate its ends. The bore V98 has an upper portion of smaller diameter to slidably accommo` date the head 106 and another central portion of larger diameter to slidably accommodate the midsection 108. The slider valve is hollow from en d to end. The lower surface of the head 106 forms a shoulder 110 and the lower surface of the portion 108 forms a shoulder 112v which, as indicated, may include a step 114. The upper surface of the portion 108 forms a shoulder 116. The effective working areas of thek shoulders 112, Y116 are substantially equal and each is greater than the effective working area of the shoulder 110. p Accordingly, if iiuid pressure is applied, as it is inthe operation of our mole, constantly to both the shoulders 110, 116, the slider will move downwardly relative to the piston, and if the* same pressure also is applied concurrently to the shoulder 112,

the slider will move upwardly relative to the piston. It

is `for this reason that we have used the adjective differ-A ential in describing the slider valve.

The mole is provided with sundry channels, bores, recesses and ducts for proper operation thereof, these hav` ing a seeming `complexity which is less than would appear from the casual examination of the drawings. In`

asmuch as an abstract description of the various passageways is somewhat difficult to follow since it is di-` vorced from the functioning of the machine, the following portion of the specification will be devoted to the operation of the fluid motor, which constitutes thecylin-k der and associated parts, the piston and its skirt and the differential slider valve. l

It is convenient to 'consider the operation of the machine by following through onecomplete cycle of operations starting with the positions of the various parts shown in Figs. l and 17 wherein the piston and the differential slider valve are at their lower extremes of travel. To

facilitate 'understanding of 'the operation of the fluid motor, all spaces which are illed with iiuid under pressure have been stippled in Figs. 17-20, and the spaces` which are connected to low pressure, that is to'say to a pressure which is lowy compared to the lluid'driving pres sure, this latter low pressure being present at Ythe outside of the mole, have been left clear, i.e., unstippled. Spaces' which are sealed oi from both high and low pressure sources have been left stippled or clear depending -upon the pressure conditions existing therein.

At the start of the cycle (see Fig. l7)`fluid under pressure flows through the annular space 42 between the upper portion of the cylinder 38 and the casing 32. The iluid streams through a series of longitudinally extending grooves 118 in the cylinder and then through a matching series of radially inwardly extending bores 120 into a long annular recess 122 on the internal surface of the cylinder. The diameter of the recess is in excess of the diameter of the upper head 124 of thepiston and said recess is in transverse registry with an annular recess 126 on the external surface of the piston below the head 124. These recesses are long enough so that they are in cornmunication in all positions of the piston. Thereby duid underpressure will at this time, and indeed at alltimes throughout the cycle of operations of the motor, ll the annular space defined by the two recesses 122, 126.

From this annular space the high pressure fluid flows radially inwardly through a series of bores 128 to the interior of the piston where it is in Contact with the slider valve and iills the recess on said valve between the shoulders 110, 116. As has been mentioned above, the high pressure working fluid'throughout the entire cycle of operation of the motor, iills this recess between said two shoulders so as to press upwardly against the shoulder 110 and to press downwardly with greater force, because of the greater area, against the shoulder 116.

Due to the fact that because of certain passageways, which soon will be described, the shoulder 112 is connected to a low pressure region (the bore in which the work is being performed) at this stage of operation, the net pressure on the slider valve now is downward so that the valve is urged to and maintained at its lowermost position with respect to the piston.

The piston includes an annular recess 130 from which ducts 132 extend longitudinally downward. These ducts now are iilled with fluid under pressure which ows from the bores 128 through the annular recess between the shoulders 110, 116 to the recess 130 and thence downwardly through the ducts 132. The lower ends of the ducts 132 open into the working chamber 78 whereby fluid under pressure thus is introduced into said working chamber -to start the piston on its upward travel relative to the stationary rod 74.

At this time the space beneath the shoulder 112 is connected through radial bores 134 in the piston to longitudinal grooves 136 on the external surface of said piston. 'I'he lower termini of the grooves 136 for the moment are below the lower end of the cylinder 38 which, as later will be seen, is connected to the bore, i.e. to low pressure, and it is for this reason that there is no high pressure on the shoulder 112. Moreover, even when the piston moves upwardly, as it immediately will from its lowermost position shown in Fig. 17, and communication is cut oi between *the low pressure side of the motor and the grooves 136 (see Fig. 18) as the lower termini of said grooves engage the bore of the cylinder 38, the slider valve still will not be urged upwardly since the mere cutoff between low pressure and the grooves 136 will not build up the high pressure on the shoulder 112 to the degree required to shift the slider valve upwardly relative to the piston.

While fluid at high pressure is flowing into the work chamber 78 to urge the piston upwardly, the upper work chamber S4 is connected to low pressure. This connection is effected by means of passageways that in part include a surface of the piston and in part include a surface of the differential slider valve whereby, as later will be observed, when the relative position of the piston and slider valve are changed, the Work chamber 54 will be disconnected from low pressure, i.e. exhaust, and connected to theuid at high pressure.

More particularly, the upper work chamber 54 is con nected to low pressure, and iluid llows from said work chamber to exhaust on upstroke ofthe piston, through the tube 58 to a transverse chamber 138 in the pistondirectly beneath the lower end of said tube. The bottom wall of said chamber is delined bya horizontal partition which vblocks the bore 98 that runs axially of the piston. However, this partition Ydoes not prevent` exhaust flow of fluid through the bore of the piston inasmuch as at the rim of the chamber 138 we provide a circular series of longitudinally downward extending bores 142, which terminate at their lower ends in a second transverse chamber 144. As the piston moves upwardly, iluid pressure in the work chamber 54 will be expelled through the tube 58 into the chamber 138,V from which it will ow through the bores 142 into the chamber 144, it being noted that the lower ends of the bores 142 are not, at this instant, blocked by the differential slider -valve 100. The exhausting iluid flows down through the hollow interior of the slider valve to the lateral opening 102 and continues on to the annular space 104 which is (as'has been pointed out hereinabove and as will be detailed hereinafter) connected to low pressure. It now wiil be appreciated that with the parts in the positions shown in Fig. 17, force is exerted in the lower work chamber 78 to raise the piston, and passageways are provided to allow iluid trapped in the upper -work chamber to be exhausted to low pres` sure.

After the piston has moved a short distance upwardly, it reaches the position shown in Fig. 18. Here, the lower ends of the grooves 136 have entered the cylinder 38 so that the connection between the shoulder 112 on the slider valve and low pressure is broken. However, no high pressure builds up on this shoulder 112 so that the net pressure acting on the slider valve still is in a downward direction, the greater pressure on the shoulder 116 overbalancing the pressure on the shoulder 110,` and the slider valve, accordingly, remains in its lowermost position with respect to the piston. It will be observed by further scrutiny of Fig. 18 that the initial upward movement of the piston and the slider valve has not changed any of the high pressure connections described with respect to Fig. 17, so that lluid under high pressure still flows through the lateral openings in the cylinder and through the lateral openings in the piston to the space between the shoulders 110, 116, and from there is led to the passageways connecting it to the lower work chamber. Indeed, as has been mentioned heretofore, regardless of the position of the piston within the cylinder and of the slider valve within the piston, high` pressure uid always will flow through the same lateral passageways in the cylinder and piston to er1-ter this space between said shoulders. In the Fig. 18 position the same route is followed as above described for the uid exhausted from the upper work chamber to low pressure.

As the piston continues to move upwardly, it nally will reach the position shown in Fig. 19, which is near the top of a stroke and in which the upper termini of the grooves 136 are transversely registered with the annular recess 122 in the cylinder. Since high pressure fluid always is present in this recess as long as the iluid motor is operating, said high pressure uid nowl will ilow through the radial bores 134, which in the Figs. 17 and 18 position of the piston were at low pressure. Fluid issuing from said bores acts upon the shoulder 112. inasmuch as the work area of this shoulder is substantially the same as the work area of the shoulder 116, the two pressures exerted on these shoulders will substantially balance one another and, therefore, the only pressure remaining to act on the slider valve now will be that of high pressure fluid pressing against the shoulder 110. This will urge the slider valve upwardly, and since the same is short and of relatively slightweight its movement will be extremely rapid. The slider valve will snap upwardly until it is in its uppermost position relative to the piston and abuts against the under surface of the partition 140, such uppermost position being illustrated in Fig. 20.

In said Fig. 20, the piston is shown after having begun its downward movement, the slider valve still being in its uppermost position in respect thereto. This ligure illustrates the change in connections that has been carried out by completion of the upward movement of the slider valve. In the lrst place, the high pressure fluid now has been ladmitted to the upper work chamber 54. The path of travel for the fluid at high pressure is from the space between the two shoulders 110, 116 of the slider valve, where, as will be seen in Fig. 20, fluid under the high pressure still is present, into the chamber 144, which has been exposed to this space by upward movement of the slider valve. In its uppermost position, the head 106 of the slider valve is above the chamber 144, thereby blocking communication from this chamber to the inside of the slider valve, which is at low pressure, while at the same time directing to said chamber the high pressure fluid. The high pressure iluid flows upwardly through the bores 142 into the chamber 138 above the partition 140, and from there it streams through the tube 58 into the upper workl chamber 54 so as to drive the piston downwardly. Y

v The same motion of the slider valve rwhich supplied uid at high pressure to the upper work chamber connects the lower work chamber 78 to low pressure. The enlarged-mid-portion 108 of the slider valve includes a series 'of radially extending openings 146. When the slider valve is in its uppermost position, these openings transversely register with the annular recesses 130 that are connected to the upper ends of the ducts 132. Thus, in such position said slider valve connects the lower worky chamber 78 to the inside of the slider valve which, as noted above, is permanently connected to low pressure. Accordingly, as the slider valve moves downwardly, fluid trapped in the lower work chamber 78 is able to exhaust freely.

' Suitable means desirably are incorporated to cushion the upper and lower ends of the strokes of the piston and slider valves. For instance, attention already has been directed to the pin `66 carried by the cap 52 and it'has been mentioned that this pin is snugly vslidably receivable in the upper end of the tube 58. By virtue of this arrangement, as the piston approaches the upper endof its travel, tluid will be trapped in the annular space around the pin 66 so as to cushion the piston before it reaches the top of its stroke. Y

As the piston approaches the lower end of its stroke, the slider valve 100 is shifted downwardly to the position shown in Fig. 17 before the piston has reached its lowermost position. This causes the slider valve to be snapped downwardly relative to the piston to the positionfshown in Fig. 17, whereby high pressure fluid immediately penetrates to the lower work chamber and prevents the crown of the skirt from striking the rod 74.

' It may be mentioned at this point that during common downward' movement of the slider valve and piston` with said elements in their relative position illustrated in Fig. 20, after the upper termini of the grooves 136 pass below the bottom of the annular recess 122, high pressure still is maintained beneaththe shoulder 112 where it balances the pressure on the shoulder 116, and these pressures remain balanced with the overriding pressure on the shoulder 110 holding the slider valve in its uppermost position until the lower termini of the grooves 136 dropout of the bore of the cylinder 38V.

As to the slider valve, it will be noted that it has a short step at its upper end which fits into a mating recess formed in the under surface of the horizontal partition 140. The edge of the recess likewise is formed witha `10' small step, and fluid trapped betweenthese steps cushions" the end of the upward movement of the 'slider valve.

A similar set of steps at the lower end of the slider valve cushions the end of the downward movement thereof.

The side walls of the skirt 50 are formed with radial bores 148, which allow egress of iluid from over the upper end of the hammer r84 as the latter moves upward 1y on an upward stroke of the piston. Without these bores, fluid would be trapped the hammer.

Fluid under low pressure exiting throughthe annular space 104 flows down through arcuate openings 150in the flange 90 into an annular space 152 between the hammer 84 and the sleeve 96. 'Ihe tapped lower end of said sleeve 96 is engaged with: the upper externally threaded end of a sleeve 154 which slidably and no n` rotatably engages the hammer. The periphery of the lower end of the hammer 84 is formed with longitudinal grooves 158. Fluid owing through the annular space 152 enters the internal bore 160 of the hammer through radially inwardly extending ducts 162, said fluid leaving the hammer through the open bottom end of said between the sleeve v68 and' bore. Fluid also liows down over the outer surface of the hammer along the grooves 158.

To the lower end of the sleeve 154, we threadedly at n tach a tube 164 which,`in turn, vsupports a ferrule tipY 166. The inside of the ferrule is threaded to engage a' clamping ring 168 that compresses a rubber sleeve 170 against a downwardly-facing step in the ferrule. Said clamping ring is held 'in place by alock nut 172. The rubber sleeve is employed toform a pressure seal bearing against the outer cylindrical surface of an anvil 174 of tubular shape, the upper end of which is adjacent the bottomv of the hammer. The bore inthe anvil is lined up with the bore in the hammer so as to permit exit of the fluid from the fluid motor. Radial bores 176 near the upper end of the anvil equalize the external and internal pressure thereon. l i

The tube 164'inoludes internal longitudinally extending ribs 177 sliding in matching grooves 178 on the anvil in order to guide the latter for axial movement and to tie the anvil to the tube for mutual rotation. It should be stated at this point that the aforesaid coupling carries the torsional load to be transmitted'from the rotating string to the tool bit, thus preventing the imposition of torsional load of a substantial nature on any of the parts in the bore of the anvil. The bore has attached to it' upwardly extending wings 186 that engage the bore of the anvil and guide the valvebody for axial movement. A compression spring 187 urges the valve disc upwardly into closed position. This spring is comparatively light and is easily compressed by the iluid leaving the motor whereby to open and hold the check valve open. However, when the mole is being lowered into a mudtlled bore, the pressure imposed at the bottom 'end of the mole as it is sunk into the earth merely closes the check valve more tightly and prevents entry of the gritty mud into the motor. i A tool holder 188 is screwed onto the lower end of the anvil.

The flange normally buttspup against a step in'the tube` 164 under the weightof the string. However the pistonk and hammer move downwardly and create a downwardly moving shock force upon hitting the anvil, the anvil andy;

coarse Tl lianger 190 will be driven downwardly' a short distance, this' distance being less than the axial length of the recess 192. i.

The mole cank be utilized for downward drilling', as in' auf oil` well or for downward, upward or horizontal drilling, as in-a mine. Moreover, it will be appreciated that, if desired, by suitably shortening the same the motor can be employed as the driving power for any percussion type mechanism suchf as, for instance, a jackhammer. In the latter circumstances, air rather than liquid is used as the high pressure fluid.

By way of example, we have shown different types of conventional bits designed to be attached to our new mole. In Fig. 14, we have illustrated a four-edged chisel bit 194, and in Fig. a` rolling bit 196, both of conventional construction, and both of the type in use for deep drilling into the earths surface. It will be appreciated that with either of these bits the rotation of the plug 34 is transmitted through the casing 32, the lower end of the cylinder 38,- the sleeve 94, the sleeve 96, the sleeve 154, and the tube 164 to turn the anvil 174, and, through the-tool holder 188, which ever bit may be carried thereby. As pointed out previously, torque for this rotation of the bit is not transmitted through the fluid motor.

Another type of bit adapted to be used with our mole is illustrated in Fig. 16. This bit, denoted by the reference numeral 198, is a crown bit formed at the end of a tube 200 which is employed to secure sample cores. lt has been observed heretofore that the fluid motor drives the hammer 84. The lower end of the hammer strikes the upper end of the anvil 174, but has no physical connection therewith. Hence, although when the piston of the motor moves sharply downward it will cause an impact-of the hammer `against the anvil, when the piston is moved retrogradely the hammer will separate from the anvil. As a result, since the upward movement of the anvil is fixed by abutment of the flange 190 against the step in the tube 164, the tube 200 will not travel upwardly when the piston lifts. The tube 200, accordingly receives only a succession of downward impacts and never any upward impacts. Heretofore when sampling by means of a tube of this nature, the core often broke or was driven out of the tube due to the upward direction of the impacts and this,- of course, has been avoided by our sigular mole.

In addition, when sampling, it often is desirable, to obtain specimens of the mud adjacent the drilling bit. We secure these through means of a Calix tube 202. Said tube 202 actually constitutes a sleeve having a cap 204 secured to its lower end. The sleeve includes a centrally upwardly extending threaded nipple 206 which engages the threads at the inside of the bottom end of the ferrule 166. Thus, the Calix tube is carried directly by the ferrule. Since the anvil impacted by the hammer in axially movable relative to the ferrule, the weight of the Calix tube is not carried by the anvil and hence the mass of the anvil is not increased by that of said tube. Thus the downward impact shock generated by the motor is not diluted by the non-working mass of the tube.

It thus will be seenA that we have provided a mole and fluid motor which achieve the various objects of our invention and are well adapted to meet the conditions of practical use.

As various possible embodiments might be made of our present invention and as various-changes might be made in theV embodiment above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is fo be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

l. A huid percussion motor comprising a first hollow cylinder having an open end and a closed end, a first piston having an end slidable in said r'st cylinder, the other end of said piston constituting a` sec-ond hollow cylinder having a`ope'1 end and a' closed end, a second piston having an end'slidable insaid second cylinder, means connecting the second piston tothe first cylinder so that it is axially immovable relative thereto, whereby two work chambers arev provided, one between the rst cylinder and first piston and the other between the second cylinder and' second piston, 'and valve means for alternately connecting said Vchambers to iiuid under pressure and for alternately reversely connecting said chambers to low pressure.

2'. A fluid percussion motor comprising a lirst'hollow cylinder having an open end and a closed end, a first piston having an end slidable in said first cylinder, the other end of said piston constituting a second hollow cylinder having an open end and a closed end, a second piston havingan end slidable in said second cylinder, means' connecting said chambers to fluid under pressure andfor alternately reversely connecting said chambers to'low pressure, a hammer, the means connecting the second piston to the first cylinder comprising a tube parallel to the direction of movement of the rst piston and having a slo't in the side thereof extending in the same direction, said hammer having a portion slidable within the tube, and means connecting said hammer to the second cylinder through said slot.

3. A motor as set forth in claim 2 wherein the second piston is mounted on the tube.

4. A fluid percussion machine comprising a casing, a first hollow cylinder within said easing and secured thereto, said cylinder having an open end and a closed end, a first piston having an end slidable in said cylinder and defining a work chamber in cooperation therewith, the other end of said piston constituting a second hollow cylinder within and spaced from said casing and having an open end and a closed end, a second piston within and secured to said casing and having an end slidable in said second cylinder to form a second work chamber, valve means for alternately connecting said work chambers to fluid under pressure and for alternately reversely conend, a first piston having an end slidable in said cylinder and defining a work chamber in cooperation therewith, the other end of said piston constituting a second hollow cylinder within and spaced from said casing and having an open end and a closed end, a second piston within and secured to said casing and having an end slidable in said second cylinder to form a second work chamber, Valve means for alternately connecting said work chambers to fluid under pressure and for alternately reversely connecting said work chambers to low pressure, means leading the exhausting fluid from said work chambers into the space betwen said second cylinder and said casing, a set of ribs within the casing defining a cage and supporting the second piston from said casing, a hammer having a portion slidable within the cage, and means extending fromv the second cylinder through the spaces between said ribs to the hammer.

6. A fluid percussion machine comprising a casing, a cylinder within and secured to said casing, a piston slidable in said cylinder, said piston being formed with a bore, a slider valve translatably located in said bore, said piston and cylinder cooperating to'define a work chamber, an elastomeric sleeve slidably sealing said work chamber, means axially compressing said sleeve, and valve means alternately supplying high pressure uid to said work l .chamber and alternately reversely connecting said chamber to low pressure.

7. A'iiuid motor comprising a cylinder and a` piston-V defining vtwo work chambers, vsaid cylinder having an internal bore, said piston having an internal bore, said piston'being'slidable relative'to said cylinder, a slider valve'slida-ble-in said piston and having a passage, saidV tions of the piston and cylinder, a second port in the.

piston-connected to 'one of said work chambers, a third port in the piston connected to the other of the work chambers, means connecting the passage of the slider valve to low pressure, means -for reciprocating said slider valve between two extreme positions within the piston, means on the slider valve for connecting the first port in the piston in-alternate extreme positions of said valve to the second and third ports in the piston, and means on the slider valve to reverselyY connect the second and third ports in thepiston to the passage of the slider valve in alternate extreme positions of said valve.

8. A uid motor comprising a cylinder and a piston defining two work chambers, said cylinder having an internal bore, said piston having an internal bore, said piston being slidable relative to said cylinder, a differential slider valve slidable in said piston and having a passage, said cylinder having a port to which fluid under pressure is continuously supplied, said piston having a port, means providing communication between said ports in all positions ofthe piston and cylinder, a second port in the piston connected to one of said work chambers, a third port in the piston connected to the other of the work chambers, means connecting the passage of the slider valve to low pressure, means for reciprocating said slider valve between two extreme positions within the piston, means on the slider valve for connecting the port in the piston in alternate extreme positions of said valve to the second and third ports in the piston, and means on the slider valve to reversely connect the second and third ports in the piston to the passage of the slider valve in alternate extreme positions of said valve.

9. A uid motor comprising a cylinder and a piston defining two work chambers, said cylinder having an internal bore, said piston having an internal bore, said piston being slidable relative to said cylinder, a slider valve slidable in said piston and having a passage, said cylinder having a port to which uid under pressure is continuously supplied, said piston having a port, means providing communication between said ports in all positions of the piston and cylinder, a second port in the piston connected to one of said work chambers, a third port in the piston connected to the other of the work chambers, means connecting the passage of the slider valve to low pressure, said slider valve including three shoulders two of which face in one direction and the other in the opposite direction, a pair of the shoulders facing in opposite directions being of substantially the same area and larger than the third shoulder, a fourth port in the piston, said fourth port connecting with the slider valve in the area of the piston bore at which one of the pair4 of shoulders is exposed, the remaining pair of shoulders having a space between them continuously connected to the first port in the piston so as constantly to have fluid under pressure therein, means alternately connecting the fourth port to low pressure and to high pressure whereby the slider valve will be reciprocated between two extreme positions within lthe piston, means on the slider Valve for connecting the port in the piston in alternate extreme positions of said valve to the second and third ports in the piston, and means on the slider valve to reversely connect the second and third ports in the piston to the passage of the slider valve in alternate extreme positions of said valve.

l0. A uid percussion machine comprising a casing, a first hollow cylinder Within said casing and secured thereto, said cylinder having an open end and a closed `14 end, 'arst piston havinga'n end'slidable in said eylinder and: defining a work chamber in cooperation therewith, the 'other end of said piston constituting a second hollowcylinder within yand spaced from said casing and having-an 'open end and a closed end, a second piston withinand secured to said casing and having an end slidabl'ein said secondcylinder to `form a second work chamber, isai'd rst piston having a bore, a slider `valve slidable 'in said first piston and having a passage,v -said rst cylinder: having a port towhich fluid under pressure is continuously supplied, said'rst piston having a port, means providing communication between said ports in all positionsv of vthey rst piston and iirst cylinder, a second port in the first piston connected to one of the work chambers, a third 'port in the first pistonfconn'ected' to the other of the work chambers, means connecting the -passagelof thelslider valve to low pressure, means for reciprocating said slider valve between two extreme positions withinlthe-irst piston, means on the sliderl valve for connecting the port in the iirst piston in alternate extreme positions of said valve to the second and third ports in the rst piston, and means on the slider valve -to reversely connect the second and third ports in the first piston to the passage of the slider valve in alternate extreme positions of said valve.

l1. A fluid percussion machine comprising a casing a first hollow cylinder within said casing and secured thereto, said cylinder having an open end and closed end a lirst piston having `an end slidable in said cylinder and defining a work chamber in cooperation therewith, the other end of said piston constituting a second hollow cylinder within and spaced from said casing and having an open end and a closed end, a second piston within and secured to said casing and having an end slidable in said second cylinder to form a second work chamber, said first piston having a bore, a slider valve slidable in said first piston and having a passage, said first cylinder having a port to which fluid under pressure -is continuously supplied, said rst piston having a port, means providing communication between said ports in all positions of the first piston and first cylinder, a second port in the rst piston connected to one of the work chambers, a third port in the rst piston connected to the other of the work chambers, means connecting the passage of the slider valve to low pressure, said slider valve having three shoulders two of which 'face in one direction and the other in the opposite direction, a pair of the shoulders facing in opposite directions being of substantially the same area and larger than the third shoulder, 'a fourth port in the irst piston, said fourth port connecting with the slider valve in the area of the bore of the first piston at which one of Ithe pair of shoulders is exposed, the remaining pair of shoulders having a space between them continuously connected -to the rst port in the first piston so as constantly to have fluid under pressure therein, means alternately connecting the fourth port to low pressure and to high pressure whereby the slider valve will be reciprocated between two extreme positions in the first piston, means on the slider valve for connecting the port in the rst piston in alternate extreme positions of said valve to the second and third ports in the first piston, and means on the slider -valve to reversely connect the second and Ithird ports in the first piston to the passage of the slider valve in alternate extreme positions of said valve.

12. A uid motor comprising a casing to which iluid under pressure is supplied, a cylinder in said casing,

said cylinder having `an internal bore, a piston cooperat-v ing with said cylinder and -slidable relative thereto to deiine two work chambers, said piston having an internal bore, a slider valve slidable in said piston and having a passage, said cylinder having a port to which fluid under pressure is continuously supplied, said piston having la port, means providing communication between said ports in all positions of the piston and cylinder, a sec- 15 ond port in the piston connected .to oneof said workv chambers, 4a third port in the piston connected to theV other of the work chambers, means connecting :the passage of the slider Valve to low pressure, means for reciprocating said slider valvebetween l,two extreme posi-` tions within the piston, means onthe slider'yalve forY connecting the port in the piston in alternateextreme positions of said valve to the second and third poor-ts in the piston, and means on the slider valvefto reversely connect Ithe second and third ports inthe' piston to the passage of the slider valve in alternate extreme positions of said valve.

13. A fluid motor comprising a cylinder and a piston defining two work chambers, said cylinder having aninternal bore, said piston having an internal bore, said piston being slidable relative to said cylinder, a slider valve slidable in said piston, said sliderY valve including three shoulders, two of which face in Yone direction `and the other in the opposite direction, a pair of shoulders facing in OPPOsite directions being of substantially the same area and larger than the third shoulder, two of said shoulders facing toward one another and beingof unequal area, means supplying 'Huid .Under pressure to YReferences Cited in the le of this patent UNITED STATES PATENTS Y1, 1 10,067

MacDonald Sept. 8, 1914 1,881,258 Bayles Oct. 4, 1932 y2,669,840 Joy Feb, 23, 1954 2,859,733 Bassinger et al. Nov. 11, 

